The present invention relates to a bio cell cleaning centrifuge, a bio cell cleaning rotor assembled in the centrifuge, and a cleaning liquid distributor assembled in the rotor.
A bio cell cleaning centrifuge is adapted for cleaning bio cell such as red blood cell by separating bio cell from remaining materials while applying a centrifugal force and by cleaning the separated bio cell with a cleaning liquid.
Conventionally, red blood cell are cleaned with a cleaning liquid such as physiological saline so as to remove unwanted antibody from a suspension for antiglobulin test in blood transfusion, cross-matching test, and screening irregular antibody. To this effect, various types of bio cell cleaning centrifuges have been proposed.
For example, laid open Japanese Patent Application Publication No.Sho-50-22693 discloses a cleaning liquid distributor for supplying cleaning liquid to a plurality of test tubes held by a plurality of test tube holders. The distributor includes a conical container and nozzles projecting radially outwardly from a bottom of the conical container. A cleaning liquid is supplied into the conical container at a central portion thereof. The nozzles are made from metal tubes embedded into the container. By the rotation of the conical container, the cleaning liquid supplied therein are ejected radially outwardly from the respective nozzles into associated test tubes.
Laid open Japanese Utility Model Application Publication No. Hei-2-81640 discloses a cleaning liquid distributor in which a distributor body is formed with a plurality of radial drilled holes. Cleaning liquid is ejected out of the drilled holes into a plurality of test tubes held by a plurality of test tube holders.
In order to perform an automatic cleaning to the bio-cell with the centrifuge for executing a desirable blood transfusion check-up, amount of cleaning liquid distributed from a cleaning liquid distributor into the respective test tubes must be equal to one another. If the supplied amount of the cleaning liquid in one test tube is smaller than the amount in the remaining test tubes, greater amount of foreign objects such as antibodies may remain in a suspension in the one test tube. On the other hand, if the supplied amount of the cleaning liquid in one test tube is greater than the amount in the remaining test tubes, amount of the residual foreign objects in the one test tube is smaller than that in the remaining test tubes. This difference in residual amount of the foreign objects may vary or affect the results of test subsequently performed by way of reagent reaction. Accordingly, precise judgment in blood transfusion test may not be achievable.
If re-supply of the cleaning liquid is performed to the specific test tube in which the cleaning liquid had not been sufficiently supplied, remaining test tubes are also subjected to re-supply of the cleaning liquid. Therefore, excessive amount of the cleaning liquid is supplied to the remaining test tubes to cause overflow of the cleaning liquid, thereby loosing precious bio-cells. If cleaning frequencies are determined based on the least amount of the cleaning liquid, cleaning process requires a prolonged period of time.
Unevenness in amount of cleaning liquid supplied into the respective test tubes occurs by several reasons. First reason resides in unevenness in flow resistance in respective fluid passages of the cleaning liquid distributor. For example, in case of the fluid passages provided by the drilled holes as disclosed in the Laid open Japanese Utility Model Application Publication No. Hei-2-81640, shape of a hole inlet, a hole outlet and surface roughness of an inner peripheral surface of the hole may be varied due to drilling. This dimensional inaccuracy leads to unevenness of flow resistance, to thus lead to variation in supplying amount to the respective test tubes. Further, in case of the cleaning liquid distributor disclosed in Laid open Japanese Utility Model Application Publication No. Hei-2-81640, an end face of the metal pipe must be subjected to machining, and length of the metal pipes may be different from one another. This leads to uneven flow resistance to thus lead to variation in supplying amount to the respective test tubes.
The second reason for providing the unevenness in amount of cleaning liquid in the test tubes resides in the leakage of the cleaning liquid from the test tubes. For example, if a distance between the cleaning liquid outlet and an open end of the test tube is too long, cleaning liquid ejected out of the outlet cannot reach the open end due to dimensional error in cleaning liquid electing direction. On the other hand, if the open ends of the test tubes are positioned excessively close to outlet ends of the metal pipes in an attempt to obtain complete entry of the cleaning liquid into the test tube, openings of the test tubes may abut the outlet ends of the metal pipes due to dimensional variation of the test tubes and horizontal rattling of the test tube holders at an initial rotational phase. This may cause breakage of the test tubes.
The third reason for providing the unevenness in amount of cleaning liquid in the test tubes resides in foreign objects contained in the cleaning liquid. Fluffy dust floating in an atmosphere may be involved in the cleaning liquid during its transportation from a pump to the cleaning liquid distributor. If such foreign objects are deposited at the pipes or holes of the distributor, the liquid passages may be blocked to reduce the supplying amount to the test tubes. If physiological saline is used as the cleaning liquid, a solid material such as a precipitated sodium chloride may block the liquid passage in the tank and the distributor to lower the flow rate of the cleaning liquid. In the conventional device, such clogging is invisible from outside. Therefore, cleaning process must be periodically stopped in order to observe the distributed amount of the cleaning liquid in the test tubes. Further, in the conventional device, cleaning liquid is always ejected out of the existing nozzles or holes regardless of the numbers of the test tubes. If numbers of the test tubes is smaller than the numbers of the test tube holders, cleaning liquid is wasted.